The present invention relates generally to motor vehicle oil sensors.
In order to prolong the life of a combustion engine, the oil which provides lubrication to the vital components within the engine must be changed at regular intervals. Most oil changes today are conducted based on schedules recommended by manufacturers of the vehicles. Due to customer desire, the intervals between oil changes are getting longer. Longer intervals reduce pollution associated with the disposal of waste oil. Similarly, reducing unnecessary oil changes helps minimize pollution due to waste oil. Unfortunately, the useful life of oil varies greatly depending on the quality of the oil, the type of engine in which the oil is disposed, the ambient conditions, and the vehicle service schedule. Moreover, contamination of the oil by antifreeze or water can severely reduce the oil""s lubrication and anti-wear functions.
As a result, the interval between oil changes may exceed the useful life of the oil and thus, it is necessary to monitor the condition of the oil between changes to ensure that the oil is still providing the necessary lubrication. If the condition of the oil has deteriorated or it is contaminated, it may be changed before the recommended time so that the engine will not be harmed.
Accordingly, electrochemical oil condition sensors have been provided that sense the condition of the oil and generate warning signals when maintenance, i.e., an oil change, is due as indicated by the condition of the oil. One such sensor is disclosed by U.S. Pat. No. 5,274,335 (the xe2x80x9c""335 patentxe2x80x9d). The ""335 patent discloses a sensor composed of two gold plated iron electrodes that are separated by a gap in which test oil is disposed. A triangular waveform is applied between the electrodes and the current induced by the externally applied potential is used as a parameter to determine the condition of the oil within the sensor.
The above-mentioned sensor, like others, however, cannot detect when the wrong oil is used to fill the oil pan or used to top off the oil pan. Moreover, these sensors cannot detect a large coolant or water leak into the oil pan, nor can they detect when the oil has been changed.
The present invention has recognized these prior art drawbacks, and has provided the below-disclosed solutions to one or more of the prior art deficiencies.
A processor for generating a signal representative of engine oil condition includes means for receiving input from at least one oil condition sensor sensing oil condition in an engine. The processor further includes means for determining that the engine is experiencing a first stage of oil degradation based on the input. The first stage of oil degradation is characterized by a first sensor output signal trend based. The processor includes means for determining that the engine is experiencing a second stage of oil degradation based on the input. The second stage of oil degradation is characterized by a second sensor output signal trend that is different from the first sensor output signal trend. Moreover, the processor includes means for determining that the engine is experiencing a third stage of oil degradation based on the input. The third stage of oil degradation is characterized by a third sensor output signal trend that is different from the first sensor output signal trend and second sensor output signal trend. The processor also includes means responsive to the means for determining for generating a signal representative of: an approach of an end of the first stage of oil degradation, an entry into the second stage of oil degradation, and an entry into the third stage of oil degradation.
In a preferred embodiment, the processor includes means for maintaining a count that represents how many consecutive times an engine has been started and then stopped without the oil temperature reaching a threshold temperature. Preferably, the processor also includes means for generating a signal based on the count. The signal based on the count is useful for indicating oil condition.